Since Light emitting diodes (LEDs) have the advantages of low production cost, simple structure, less consuming power, small size and easy installation, they are widely applied in light sources and display devices.
Traditionally, an LED includes an LED epitaxy structure, a reflective layer and an ohmic contact layer, which are sequentially formed on a substrate. The LED epitaxy structure includes an n-type semiconductor layer, an active layer and a p-type semiconductor layer. The reflective layer is used to reflect lights produced from the LED epitaxy structure, making lights emit toward a same direction and increasing the brightness of the LED. Silver having high reflective index, is therefore widely used as the material of the reflective layer. However, silver may migrate into the LED epitaxy structure as time elapses, causing the leakage of electricity and decreasing the performance of the LED. Therefore, the ohmic contact layer over the reflective layer is provided to prevent silver from migrating into the LED epitaxy structure.
In addition, peelings may occur between the reflective layer and the LED epitaxy structure due to poor adhesion between silver and the LED epitaxy structure, and cracks may also occur between each layer in the LED epitaxy structure due to variation of the process temperature during a conventional lift-off step for the substrate.
Therefore, there is a need to provide a light emitting diode and its fabricating method to enhance the adhesion between the reflective layer and the LED epitaxy structure or between each layer in the LED epitaxy structure.